#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<map>
#include<queue>
#include<string>
#include<sstream>
#include<cmath>
#include<numeric>
using namespace std;

int a = 0;

int dfs(int sy, int sx, int gy, int gx, vector< vector<int> > m, vector< vector<bool> > f, int p){
  int dx[4] = {0, 1, 0, -1};
  int dy[4] = {-1, 0, 1, 0};
  if( sy == gy && sx == gx && p >= 3){
    a++;
    return a;
  }

  for(int i=0; i<4; i++){

    if( !f[ sy+dy[i] ][ sx + dx[i] ] && m[ sy+dy[i] ][ sx + dx[i] ] != 0 ){
      f[ sy+dy[i] ][ sx+dx[i] ] = true;
      dfs(sy+dy[i], sx+dx[i], gy, gx, m, f, p+1);
    }

  }
  return 0;
}


int main(){

  int n;
  cin >> n;
  vector< vector<int> > m(120, vector<int>(120, 0));
  for(int i=0; i<n; i++){
    int r0, c0, r1, c1;
    cin >> r0 >> c0 >> r1 >> c1;

    m[r0][c0]++;
    m[r1][c1]++;
    // if( m[r0][c0] >= 3 || m[] )
  }
  vector< vector<bool> > f(120, vector<bool>(120, false));
  for(int i=1; i<115; i++){
    for(int j=1; j<115; j++){

      if( m[i][j] != 0 ){
        dfs(i, j, i, j, m, f, 0);
      }
      if( a >= 2 ){
        cout << "NO" << endl;
        return 0;
      }
      a = 0;
    }
  }
  cout << "YES" << endl;

  return 0;
}